Brominated materials

ABSTRACT

Described are (alkyl,bromo)phenoxy alkyl(meth)acrylate monomers and polymers made therefrom.

FIELD OF THE INVENTION

The invention relates to (alkyl,bromo)phenoxy alkyl(meth)acrylatemonomers and polymers made therefrom.

BACKGROUND

Reactive chemical monomers can be used to prepare polymeric materialswhich have various properties and which are useful for variousapplications. As one example, monomers having optical properties cangenerally be used, alone or in combination with other reactivematerials, to produce useful products having a high index of refraction,and that are useful to control the flow and intensity of light. Tocontinually improve such products, or the processes for preparing suchproducts, there is an ongoing need to develop new and improved highindex of refraction monomeric materials.

Some brominated aromatic (meth)acrylate monomers have been found to beuseful as high index of refraction monomers. These monomers can exhibitdesirable optical qualities, but generally tend to display relativelyhigh melting points, and therefore exist as solids at temperatures nearroom temperature (e.g., in the range from about 20 to 30C). Often suchknown brominated monomers have melting points significantly above roomtemperature. In addition, polymerization of these monomers (bythemselves or with other comonomers) can frequently lead to a polymerwith a relatively high glass transition temperature (Tg) which can limitthe range of application of such monomers.

It would be desirable to identify monomers useful to produce opticalmaterials, where the monomers have physical properties including arelatively high index of refraction, a relatively low melting point incombination with a relatively low room temperature viscosity, and whichcan be used to prepare polymers (e.g., homopolymers or copolymers)havinga relatively low Tg.

SUMMARY OF THE INVENTION

The invention provides (alkyl,bromo)phenoxy alkyl(meth)acrylatemonomers. The term (alkyl,bromo)phenoxy alkyl(meth)acrylate is usedherein to refer to chemical compounds comprising a (meth)acrylate, aphenoxy ring substituted with at least bromine and an alkyl group, and adivalent alkylene group connecting the (meth)acrylate to the phenoxyring. Preferred monomers exhibit a relatively high index of refraction;i.e., at least 1.50. Preferred monomers also have a relatively lowmelting temperature; i.e., below about 60 degrees celsius (60C), morepreferably below about 35C or 30C, and most preferably exist as a liquidat or near normal room temperature (e.g., 25C). In addition, preferredmonomers have a relatively low room temperature viscosity, and can bepolymerized, either alone or in combination with one or more othercomonomers, to prepare polymers with a relatively low glass transitiontemperature (Tg), e.g., <50C.

An aspect of the invention relates to (alkyl,bromo)phenoxyalkyl(meth)acrylate monomers such as those having the general formula:

wherein m is from 1 to 4; R2 is hydrogen or methyl, R1 is a straight orbranched alkyl having at least two carbon atoms, and L is a straight orbranched alkylene.

Another aspect of the invention relates to a polymerizable compositioncontaining an (alkyl,bromo)phenoxy alkyl(meth)acrylate monomer such asthat defined directly above. The polymerizable composition can furthercontain one or more other comonomer.

Yet another aspect of the invention relates to a polymer or polymericmaterial comprising a chemical segment having the formula:

wherein m is from 1 to 4, R2 is —H or methyl, R1 is a straight orbranched alkyl having at least two carbons, and L is a straight orbranched alkylene. Such a polymer can be prepared by polymerization ofthe (alkyl,bromo)phenoxy alkyl(meth)acrylate monomer.

As used within the present description, “monomer” refers to a monomer onan individual (i.e., molecular) scale, and also to a composition of suchmonomers on a macroscopic scale such that the composition can bedescribed as having a physical state of matter (e.g., liquid, solid,etc.) and physical properties (e.g., melting point, viscosity, glasstransition temperature (of a polymeric form), and index of refraction).

“Index of refraction,” or “refractive index,” refers to the absoluterefractive index of a material (e.g., a monomer), which is understood tobe the ratio of the speed of electromagnetic radiation in free space tothe speed of the radiation in that material, with the radiation being ofsodium yellow light at a wavelength of about 583.9 nanometer (nm). Indexof refraction can be measured by known methods, and is generallymeasured using an Abbe Refractometer.

“Glass transition temperature,” (Tg), is the temperature range overwhich a thermoplastic polymer changes from a brittle, glass state to aplastic state. Tg can be measured by methods known in the analyticalchemistry art, such as the method described in the Examples sectionbelow.

“(Meth)acrylate” refers to both acrylate and methacrylate compounds.

DETAILED DESCRIPTION

Monomers of the invention include (alkyl,bromo)phenoxyalkyl(meth)acrylate monomers, wherein the alkyl group includes at leasttwo carbon atoms (also referred to herein as “the monomer” or “thebrominated monomer,” in both singular and plural forms). The(alkyl,bromo)phenoxy alkyl(meth)acrylate monomer can comprise a(meth)acrylate, a phenoxy ring substituted with substituents comprisingbromine and an alkyl group, and a divalent alkylene group connecting thetwo.

The alkyl group can be straight or branched, and can preferably havefrom 2 to about 12 carbon atoms, more preferably from about 3 to about12 carbon atoms. The size, position, and structure of the alkyl groupare believed to affect properties of the monomer and polymers preparedtherefrom, including the refractive index and viscosity of the monomer,and the refractive index and Tg of a polymer made from the monomer. Forexample, relatively larger or more branched alkyl groups can providemonomers capable of being polymerized to polymers having relativelylower glass transition temperatures, compared to otherwise similarmonomers having fewer carbon atoms or less branching. Additionally, arelatively larger alkyl group can result in a monomer or polymer havinga relatively lower index of refraction as compared to a similar monomerhaving a relatively smaller alkyl group.

The alkylene group can generally be any divalent organic hydrocarbongroup. The alkylene group can be straight or branched, and preferredalkylene groups can contain from about 1 to about 12 carbon atoms, morepreferably from about 2 to about 6 carbons. The size and chemicalstructure of the alkylene group can affect the physical properties ofthe monomer and a polymer prepared therefrom, including the refractiveindex and viscosity of the monomer and the refractive index and Tg of apolymer prepared from the monomer. A relatively larger alkylene groupcan result in a monomer or polymer having a relatively lower index ofrefraction as compared to an otherwise similar monomer having arelatively smaller alkylene group. Relatively larger or more branchedalkylene groups can provide a monomer which when polymerized has arelatively lower Tg compared to a polymer prepared from otherwisesimilar monomers having relatively smaller or less branched alkylenegroups.

Bromine substitution can affect the index of refraction of the monomer.It is generally understood that bromine increases the index ofrefraction of the monomer. Bromine can be substituted on the aromaticportion of the monomer in any available amount or position, and willpreferably be present in an amount to provide a monomer having arelatively high index of refraction, preferably at least about 1.50.This can be accomplished, for example, by having at least two brominesdirectly attached to the aromatic ring.

Often, the position of the bromine can be a function of the materialsand process used to prepare the brominated monomer (e.g., as describedinfra). Also, the position of an alkyl group on the aromatic ring canaffect at least in part the position of bromines attached directly tothe aromatic ring. If an alkyl group is attached at the 4 positionrelative to the ester substituent (para-), two bromines can preferablybe located at the 2 and 6 position, and, if the alkyl group is at the 2position (ortho-), bromines are preferably at the 4 and 6 positions.

Examples of useful (alkyl,bromo)phenoxy alkyl(meth)acrylate monomersinclude those having the structure of formula 1:

wherein:

R2 can be hydrogen (—H) or methyl (—CH₃);

m can be from about 1 to 4, and is preferably about 2;

L can be a straight chain or branched alkylene group, preferablycontaining from 1 to about 12 carbon atoms, more preferably from about 2to about 6 carbon atoms; and

R1 can be a straight or branched alkyl having at least 2 carbon atoms,preferably having at least 3 and up to about 12 carbon atoms. R1 can bepositioned ortho, meta, or para to the phenoxy oxygen.

The monomer preferably exhibits desired properties of index ofrefraction, melting point, and viscosity. The monomer preferablyexhibits an index of refraction of at least about 1.50. The meltingpoint of the monomer can be below about 60C, preferably below about 35Cor 30C, and most preferably the monomer exists as a liquid at or nearnormal room temperature. The monomer can have a room temperatureviscosity that allows the monomer or a polymerizable composition thereofto be processed, e.g., pumped, circulated, extruded, coated, formed,cured, or otherwise handled, at or near room temperature. Althoughviscosities outside of the following ranges can be useful, preferredviscosities of the monomer can be in the range from about 20 to 5000centipoise (cps), more preferably from about 50 to 1000 cps, as measuredat 23C. Also, preferred monomers can be polymerized or copolymerized toprovide polymeric materials having relatively low Tg, e.g., below about50C. Particularly preferred monomers have both a relatively high indexof refraction (e.g., greater than about 1.50), and can produce a polymerhaving a relatively low Tg (e.g., below about 50C).

Examples of useful monomers of the invention include monomers wherein R1is located ortho to the phenoxy oxygen, as illustrated by formula 2:

In formula 2, R2, m, L, and R1 are as defined supra. In a particularlypreferred embodiment, bromine atoms are located at the 4 and 6 positionson the phenoxy ring, ortho and para to the phenoxy oxygen atom, asillustrated by formula 3:

Particularly preferred monomers of formula 3 include4,6-dibromo-2-alkylphenoxy alkylene(meth)acrylates wherein the R1 alkylhas from 3 to 4 carbons, including monomers of the types shown informulas 4 and 5, wherein R2 and L, are as defined:

With R2 as hydrogen and L as ethylene these become2-(4,6dibromo2-sec-butylpenoxy)ethyl acrylate:

 and 2-(4,6-dibromo-2-isopropylphenoxy)ethyl acrylate:

With R2 as hydrogen and L as hexylene these become6-(4,6-dibromo-2-sec-butylpenoxy)hexyl acrylate:

 and 6-(4,6-dibromo-2-isopropylphenoxy)hexyl acrylate:

(Alkyl,bromo)phenoxy alkyl(meth)acrylate monomers of the invention canbe prepared by methods generally useful in preparing substituted (e.g.,brominated) phenoxy compounds and (meth)acrylate monomers. Such methodsare well known in the organic chemistry art.

As an example of one method of preparing the monomers of the invention,the following steps can be used. First, an alkyl-substitutedphenol(alkylphenol) can be brominated to produce a brominatedalkylphenol, as desired to prepare the desired brominated monomer.

Alkylphenols are commercially available from Schenectady InternationalInc., Chemical Division, Schenectady, N.Y. Alkylphenols can bebrominated by methods that are known in the organic chemistry art, andas described, for example, in the Kirk-Othmer Encyclopedia of ChemicalTechnology, Volume 4, 543 (4^(th) ed. 1992).

The brominated alkylphenol can be alkylated by known methods to producean (alkyl,bromo)phenoxy alkanol compound.

Alkylation methods are known in the chemical art, and are generallyaccomplished by introducing an alkylating agent, for example any one ofan alkylene carbonate (e.g., ethylene carbonate), a chloroalkanol (e.g.,chloroethanol) or an alkylene oxide (e.g., ethylene oxide) to thebrominated alkylphenol under proper conditions to allow the alkylatingagent to react with the phenol alcohol and cause alkylation. See, e.g.,U.S. Pat. No. 2,448,767; and Kirk-Othmer, Encyclopedia of ChemicalTechnology, Vol. 6, 146 (4^(th) ed. 1992).

Also using methods known in the organic chemistry art, the resulting(alkyl,bromo)phenoxy alkanol compound can be esterified to give abrominated (meth)acrylate monomer:

Esterification reactions are well known in the chemical art, and aredescribed, for example, in the Kirk-Othmer Encyclopedia of ChemicalTechnology, vol. 1, 291 (4^(th) ed. 1992).

A preferred step in the preparation of the brominated monomer can be apurification step. Purification can be accomplished by any method knownin the organic chemistry art, including methods of chromatography anddistillation. For some brominated monomers, for example those that mightsuffer from thermal breakdown at elevated temperatures, it can bepreferred to purify the monomers using ultra-high vacuum continuousdistillation methods. These processes can be accomplished at pressuresin the range from about 1 to 1000 micron mercury (Hg), and temperaturesin the range from about 100 to 200C.

The brominated monomer of the invention, alone or in combination withother materials such as other unsaturated polymerizable comonomers, canbe included in a polymerizable composition that can be polymerized orco-polymerized to produce useful polymers or copolymers. As used withinthe present description the term “polymerizable” refers to chemicalcompounds such as monomers and oligomers, etc., and chemicalcompositions, capable of polymerizing or copolymerizing (e.g., viaunsaturated moieties) to produce a higher molecular weight material suchas an oligomer, polymer, prepolymer, or polymeric material. The terms“polymer” and “polymeric material” are used interchangeably to refer tomaterials prepared from the reaction of one or more polymerizablematerials, e.g., one or more polymerizable monomer, oligomer, polymer,or prepolymer, etc. to produce a dimer, trimer, oligomer, copolymer,homopolymers, etc.

Useful comonomers to be reacted with acrylic monomers such as thebrominated monomer described herein are known in the organic chemistryart, and can include any of a number of known and useful polymerizablemoieties, e.g., vinyl, (meth)acrylate, N-vinyl, acrylic acid,methacrylic acid, allyl, acrylamide, acrylonitrile, etc. The comonomercan be mono- or multifunctional with respect to the unsaturated moiety,and where multifunctional, the unsaturated moieties need not be ofidentical chemistry.

Specific types of comonomer useful in the polymerizable composition caninclude the class of (meth)acrylate-functional comonomers such asbutyl(meth)acrylate, as well as vinyl comonomers such as methyl styrene.The particular comonomers included in any given polymerizablecomposition, their molecular weight or weights, and the included amountsof each, can be chosen according to various factors such as the desirednature and properties of the polymerizable composition and the desiredproperties of the polymer or polymeric material to be prepared therefrom(e.g., index of refraction, glass transition temperature, melting point,viscosity, etc., of the polymerizable composition or polymericmaterial).

The polymerizable composition can also contain other ingredients that,as will be appreciated by those skilled in the art of polymericmaterials, can be useful in such a polymerizable composition. Forexample, the polymerizable composition might contain a crosslinkingagent, one or more surfactants, pigments, fillers, polymerizationinhibitors, or other ingredients that can be useful within apolymerizable composition or an optical product. Such ingredients can beincluded in the composition in amounts known to be effective for theirrespective purposes.

A crosslinking agent can be useful to increase the glass transitiontemperature of the polymer resulting from crosslinking the polymerizablecomposition. Glass transition temperature of a composition can bemeasured by methods known in the art, such as Differential ScanningCalorimetry (DSC), modulated DSC QMSC), or Dynamic Mechanical Analysis(DMA).

Polymeric beads, inorganic fillers, and/or pigments can be added to thepolymerizable composition in order to improve processing, to impart slipand scratch resistance to the polymerized material, or to affect opticalproperties of the polymerized material. Examples of useful polymericbeads include those made of polystyrene, polyacrylates, copolymers ofstyrene and acrylates, polyethylene, polypropylene,polytetrafluoroethylene, or combinations thereof. Examples of inorganicfillers and pigments include solid or hollow glass beads, silica,zirconia, aluminum trihydroxide, and titanium dioxide.

The polymerizable composition can preferably have a room temperatureviscosity that allows the polymerizable composition to be processed,e.g., pumped, circulated, extruded, coated, formed, cured, or otherwisehandled, at or near room temperature. Although viscosities outside ofthe following ranges can also be useful, preferred viscosities of thepolymerizable composition can be in the range from about 20 to 5000centipoise (cps), more preferably in the range from about 50 to 1000cps, as measured at 23C.

Polymerization of the composition can be accomplished by known and usualmeans, such as heating in the presence of a free-radical initiator,irradiation with electromagnetic radiation such as ultraviolet orvisible light in the presence of suitable photoinitiators, and byelectron beam. For reasons of convenience and production speed, apreferred method of polymerization might be by irradiation withultraviolet or visible light in the presence of photoinitiator.

Polymeric materials (i.e., homopolymers or copolymers) prepared from thebrominated monomer can exhibit a relatively low Tg, e.g., below aboutSOC.

The invention will be more fully appreciated with reference to thefollowing non-limiting examples in which the reaction components aregiven as grams used or as weight percents (wt %), based on the totalweight of the reaction mixtures which are nominally 100 weight %.Dimensions in English units are nominal and conversion to metric unitsis approximate.

EXAMPLE 1 Synthesis of 2-(4,6-dibromo-2-sec-butylphenoxy)ethyl acrylate

A. Preparation of 4,6dibromo-2-sec-butylphenol (DBsBP) (bromination)

In a 12 liter round bottom flask equipped with a mechanical stirrer,condenser, nitrogen cap, addition funnel and temperature probe, 1500 g(grams) of 2-sec-butylphenol was mixed with 4500 g of deionized water.The mixture was stirred with a mechanical mixer and purged with nitrogenfor about 10 minutes. 3319 g bromine was added to the mixture drop-wisethrough the addition funnel. The temperature was maintained at about 30Cor less using an ice bath. Following addition of the bromine, thereaction mixture was stirred for one hour at room temperature. Reactioncompletion was determined by gas chromatography, by monitoring thedisappearance of the starting material, 2-sec-butylphenol, and ofmonobrominated species.

Upon completion of the reaction, 3960 g of ethyl acetate was added. Themixture was stirred for 15 minutes and then allowed to phase split. Thebottom (aqueous) layer was removed and 2686 g of a 13 wt % aqueoussodium hydrosulfite solution was added. The mixture was stirred well andthen allowed to phase split. The bottom (aqueous) layer was removed and2760 g of a 15 wt % aqueous sodium carbonate solution was added. Themixture was stirred well and then allowed to phase split. The bottom(aqueous) layer was removed and solvent was stripped from the top layerusing a rotary evaporator. This procedure provided approximately 2647 gof DBsBP.

B. Preparation of 2-(4,6-dibromo-2-sec-butylphenoxy)ethanol (alkylation)

A 500 ml round bottom flask was equipped with a magnetic stirrer,condenser and temperature probe. 40 g of the4,6-dibromo-2-sec-butylphenoxy, 12.5 g ethylene carbonate and 13.1 gtriethylamine were added to the flask. The mixture was heated to reflux(˜120C) and held at that temperature for about 24 hours. At this point,gas chromatograph analysis showed only 0.9% residual starting material,so the reaction was cooled to room temperature. 170 g t-butyl methylether was added, then 20.1 g of 37% HCl in 150 g of DI water was added.The mixture was shaken well and allowed to phase split and the loweraqueous phase removed. The mixture was then washed with a solution of150 g water and 15 g of sodium carbonate and the lower aqueous phase wasremoved. The solvent was remove using a rotary evaporator to yield about40 grams of dark intermediate product. This product batch distilledusing a 163C pot, 115C overhead condenser and 0.2mm Hg vacuum to yieldthe yellow desired product, 2-(4,6-dibromo-2-sec-butylphenoxy)ethanol.

C. Preparation of 2-(4,6-dibromo-2-sec-butylphenoxy)ethyl acrylate(esterification)

A 500 ml round bottom flask was equipped with a mechanical stirrer,Dean-Stark trap, condenser, and temperature probe. 25 g of2-(4,6-dibromo-2-sec-butylphenoxy)ethanol, 125 g of toluene, 0.58 g ofp-toluene sulfonic acid, 5.5 g of acrylic acid and ˜200 ppm each ofmethyl hydroquinone and hydroquinone were mixed together in the flask.The mixture was heated to reflux to azeotrope out the water generatedduring esterification. After 5 hours, gas chromatography analysis showedthe reaction to be substantially complete (>98%). The reaction mixturewas cooled washed three times: first with a solution of HCl in water,then with a solution of NaCO₃ in water and finally with a solution ofNaCl in water and the toluene was then stripped in vaccuo. The productwas purified using continuous distillation on a rolled film evaporator(available from UIC Inc. of Joliet, Ill.) at the following conditions: 1micron Hg vacuum and 130C to obtain the product with >98% purity by NMR.

EXAMPLE 2 Preparation of 6-(4,6-dibromo-2-isopropylphenoxy)hexylacrylate

A. Preparation of 4,6-dibromo-2-isopropylphenol (DBiPP) (bromination)

The procedure describing the preparation of DBsBP was followed using1400 g of 2-isopropylphenol instead of the 2-sec-butylphenol, 4630 g ofwater, 3417 g of bromine, 4075 g of ethyl acetate, 2765 g of 13% (w/w)aqueous sodium hydrosulfite and 2842 g of 15% (w/w) aqueous sodiumcarbonate to produce 2556 g of DBiPP.

B. Preparation of 6(4,6-dibromo-2-isopropylphenoxy)hexanol (alkylation)

A 12 liter, four neck, round bottom flask was set up with a mechanicalstirrer, condenser, temperature probe and addition funnel in a coolingbath. 800 grams of 4,6-dibromo-2-isopropylphenol (DBIPP) was added tothe flask along with 4902 grams of deionized water and 408 grams ofsodium iodide. Using the addition funnel, 435 grams of a 50% sodiumhydroxide solution was added while maintaining the temperature below25C. The cooling bath was then removed and the reaction mixture washeated to reflux (100C). Using a clean addition funnel, 744 grams of6-chlorohexanol was added over 1 hour and 30 minutes. The reaction wasmixed two more hours at which point gas chromatography (GC) analysisindicated 0.3 % of the starting DBiPP remained unreacted. The solutionwas cooled and left at room temperature (22-25C) overnight.

4196 grams of ethyl acetate was added to the reaction flask and mixedfor 10 minutes (t-butyl methyl ether or other suitable organic solventmay be used). The mixture was allowed to phase split. The bottom aqueouslayer was removed by vacuum and the pH was recorded at 11. The washingstep was repeated a second time using a solution of 27 grams of 37% HClin 980 grams of deionized water. The aqueous phase that was removed hada pH of 1. The washing step was repeated a third time using 980 grams ofa 3% (w/w) aqueous sodium carbonate solution. Again the aqueous phasewas removed and the pH was recorded at 11. The final washing was donewith a 4.7% (w/w) aqueous solution of sodium chloride (982 grams). Theaqueous phase was again removed by vacuum. The organic phase filteredand concentrated on a rotary evaporator using a water aspirator.Residual solvent was removed using a vacuum pump while stirring theconcentrate with a magnetic stirrer. 1250 grams of a yellow liquid wasobtained. The yellow liquid was purified by continuous distillationusing a rolled film evaporator. First 6-chlorohexanol and 6-iodohexanolwere removed at the following conditions: 130C oil bath and 5-20 micronsHg vacuum. The residue was then continuously distilled on the rolledfilm evaporator using the following conditions: 130C oil bath and 1micron Hg vacuum. 832 grams of the water white alkylated product(6-(4,6-dibromo-2-isopropylphenoxy)hexanol) was recovered. It can benoted here that optionally, a wiped film evaporator can be used in placeof the rolled film evaporator.

C. Preparation of 6-(4,6-dibromo-2-isopropylphenoxy)hexyl acrylate(esterification)

A five liter, four neck round bottom flask was equipped with amechanical stirrer, Dean Stark trap, condenser and temperature probe.The flask was charged with 600 grams of6-(4,6-dibromo-2-isopropylphenoxy)hexanol; 2805 grams of toluene; ˜200ppm each of methyl hydroquinone and hydroquinone; 15.2 grams p-toluenesulfonic acid and 131 grams acrylic acid. This mixture was heated toreflux with stirring to azeotrope the water. After six hours ofrefluxing, 30 ml of water had been removed and 99.2% of the6-(4,6-dibromo-2-iso-propylphenoxy)hexanol had been converted to the6-(4,6-dibromo-2-iso-propylphenoxy)hexyl acrylate based on gaschromatography (GC) analysis. The solution was then cooled and allowedto mix overnight.

828 grams of a 0.27% HCl solution was added to the reaction flask andmixed for five minutes. The mixture was allowed to phase split and theaqueous bottom phase (pH=1) was removed by vacuum. The washing wasrepeated by adding 903 grams of an 8.9% (w/w) aqueous solution of sodiumcarbonate. The aqueous phase was removed after phase separation. A thirdwash was done using 867 grams of a 5.1% (w/w) aqueous sodium chloridesolution. The aqueous phase was again removed by vacuum. The organicphase was filtered and concentrated on a rotary evaporator using a wateraspirator. Residual solvent was removed using a vacuum pump whilestirring the concentrate with a magnetic stirrer. 650 grams of a hazy,light yellow liquid was obtained. The yellow liquid was then purified bycontinuous distillation in a rolled film evaporator using the followingconditions: 175C oil bath and 1 micron Hg vacuum to give the water whiteproduct. NMR analysis indicated a 98.8% purity prior to distillation anda purity of >99% in the distilled product,6-(4,6-dibromo-2-iso-propylphenoxy)hexyl acrylate.

EXAMPLE 3 Preparation of a mixture of 2-(4,6-dibromo-2-sec-butylphenoxy)2-methyl ethyl acrylate and 2-(4,6-dibromo-2-sec-butylphenoxy) 1-methylethyl acrylate

A. Preparation of 4,6-dibromo-2-sec-butylphenol (DBSBP) (bromination)

4,6-dibromo-2-sec-butylphenol (DBsBP) was prepared according to theprocedure described in Example 1.

B. Preparation of a mixture of 2-(4,6-dibromo-2-sec-butylphenoxy)2-methyl ethanol and 2-(4,6-dibromo-2-sec-butylphenoxy) 1-methyl ethanol(alkylation)

A 500 ml round bottom flask was equipped with a magnetic stirrer,condenser and a temperature probe. The flask was charged with 60 gramsof 4,6-dibromo-2-sec-butylphenol (DBsBP), 21.9 grams of propylenecarbonate, and 19.7 grams of triethylamine. The mixture was heated toreflux (120C) and held at that temperature for about 24 hours. Themixture was cooled to room temperature and the flask was charged with170 grams of t-butyl methyl ether. 170 grams of a 4.3% aqueous solutionof HCl was added to the reaction flask and mixed. The mixture wasallowed to phase separate and the aqueous phase was removed. 165 gramsof a 9.1% aqueous solution of sodium carbonate was then added to theflask, mixed and allowed to phase separate. The aqueous phase was againremoved. The ether solvent was then removed using a rotary evaporator.68 grams of dark alkylated product was recovered. ¹³C NMR analysisindicated the recovered product to be predominately a mixture of2-(4,6-dibromo-2-sec-butylphenoxy) 2-methyl ethanol and2-(4,6-dibromo-2-sec-butylphenoxy) 1-methyl ethanol.

C. Preparation of a mixture of 2-(4,6-dibromo-2-sec-butylphenoxy)2-methyl ethyl acrylate and 2-(4,6-dibromo-2-sec-butylphenoxy) 1-methylethyl acrylate (esterification)

A five liter, four neck round bottom flask was equipped with amechanical stirrer, Dean Stark trap, condenser and temperature probe.The flask was charged with 25 grams of the intermediate alkylatedproduct from example 3B, 125 grams of toluene, 5.9 grams of acrylicacid, 0.58 grams p-toluene sulfonic acid, and about 200 ppm each ofmethyl hydroquinone and hydroquinone. The mixture was heated to refluxto azeotrope out the water generated during esterification. Gaschromatography analysis after three hours of reflux showed only slightconversion. The toluene was then stripped using a rotary evaporator andan equal amount of xylenes were added back to the flask. This mixturewas then heated to reflux (˜140° C.) to azeotrope out water. After onehour, gas chromatography showed 33% conversion of the alcohol. Acrylicacid (2 grams) was added to the flask and reflux was continued anadditional an additional two hours. At this point, the conversionwas >90%. The reaction mixture was then cooled and washed as describedin Section 1C above, and the xylenes were stripped using a rotaryevaporator. The crude product remaining in the evaporator flask waspassed through a flash chromatography column using methylene chloride toisolate the desired product. The solvent was again removed using arotary evaporator. Residual solvent was removed using a vacuum pumpwhile stirring the concentrate with a magnetic stirrer. ¹³C NMR analysisof the product showed a mixture of 2-(4,6-dibromo-2-sec-butylphenoxy)2-methyl ethyl acrylate (˜77%) and 2-(4,6-dibromo-2-sec-butylphenoxy)1-methyl ethyl acrylate (˜11%).

EXAMPLES 4-16

Using bromination, alkylation and esterification steps similar to thosedescribed in Examples 1 to 3, a variety of (alkyl,bromo)phenoxyalkyl(meth)acrylate monomers were prepared. By using appropriatestarting materials, stoichiometric quantities, and the methods describedin Examples 1-3, one skilled in the art of organic chemistry couldprepare the materials of Examples 4-16 outlined in Table 1.

TABLE 1 Synthesized Monomers Example Name 1 2-(4,6-dibromo-2-sec-butylphenoxy) ethyl acrylate 2 6-(4,6-dibromo-2-isopropyl phenoxy) hexylacrylate 3 2-(4,6-dibromo-2-sec-butyl phenoxy) 2-methyl ethyl acrylateand 2-(4,6-dibromo-2-sec-butyl phenoxy) 1-methyl ethyl acrylate 46-(4,6-dibromo-2-sec-butyl phenoxy) hexyl acrylate 52-(4,6-dibromo-2-isopropyl phenoxy) ethyl acrylate 66-(4,6-dibromo-2-dodecyl phenoxy) hexyl acrylate 72-(4,6-dibromo-2-dodecyl phenoxy) ethyl acrylate 82-(2,6-dibromo-4-nonyl phenoxy) ethyl acrylate 92-(2,6-dibromo-4-dodecyl phenoxy) ethyl acrylate 106-(4,6-dibromo-2-sec-butyl phenoxy) hexyl methacrylate 116-(4,6-dibromo-2-isopropyl phenoxy) hexyl methacrylate 122-(4,6-dibromo-2-sec-butyl phenoxy) ethyl methacrylate 132-(4,6-dibromo-2-isopropyl phenoxy) ethyl methacrylate 142-(4,6-dibromo-2-dodecyl phenoxy) ethyl methacrylate 152-(2,6-dibromo-4-nonyl phenoxy) ethyl methacrylate 162-(2,6-dibromo-4-dodecyl phenoxy) ethyl methacrylate

Experimental Methods

Homopolymerization—Homopolymers of several of the above noted monomerswere prepared by combining 2 grams of monomer with 10 grams of ethylacetate solvent and 0.006 grams of Vazo 64 or Vazo 88 initiatior(available from Dupont) in a 4 once (118.3 ml) glass bottle. The bottlewas purged for one minute with nitrogen at a flow rate of one liter perminute. The bottle was sealed and then placed in a rotating water bathat 55C (65C if Vazo 88 initiator was used) for 24 hours to effectessentially complete polymerization. The homopolymer was recovered forTg analysis by evaporating the solvent at 105C.

Glass Transition (Tg)—Glass transition temperatures (Tg) were determinedusing a differential scanning calorimeter (DCS-7) manufactured by PerkinElmer, Norwalk, Conn. A 10 mg polymer sample was heated at a rate of20C/minute, cooled at a rate of 40C/minute and then reheated at20C/minute. The Tg was calculated on the second heating cycle.

Viscosity—Steady shear viscosity measurements were made at 25C using a40 mm parallel plate fixture on Rheometrics Stress Rheometer (DSR) whichis a commercially available instrument sold by Rheometrics, Scientific,One Possumtown Rd., Piscataway, N.J. 08854. The sample of monomer wassandwiched between the two plates and squeezed out till a gap setting of0.45 to 0.5 mm was achieved. The excess material was cleaned out and thesample was then subjected to a set of predetermined shear rates. At eachshear rate, the viscosity measurement was made when the torque was atsteady state. Analysis indicated the viscosity to be independent of theshear rate. The viscosity was reported in Table 2 in centipoise (cps).

Refraction Index—The refractive index of resin compositions and curedfilms were measured using an Abbe Refractometer, made by Erma Inc. ofTokyo Japan and distributed by Fisher Scientific.

TABLE 2 Properties of Monomers and Homopolymers Monomer MonomerRefractive Viscosity, Tg of Homopolymer Example Index (cps) (° C.) 11.5455 120 33 2 1.5340 90 −10 3 1.5432 4 1.5265 90 −20 5 1.5490 120 61.5135 80 7 1.5210 80 8 1.5355 ˜1000 9 1.5280 ˜1000 10 1.5300 ˜100 111.5335 ˜100 7 12 1.5460 120 39 13 1.5470 120 14 1.5120 Solid 15 1.5330˜1000 16 1.5280 ˜1000

What is claimed is:
 1. A monomer of the formula:

wherein m is from 1 to 4, R2 is H or methyl, R1 is a straight orbranched alkyl having at least 2 carbons, and L is a straight chain ofbranched alkylene.
 2. The monomer of claim 1 selected from the groupconsisting of


3. Monomer of claim 1 wherein R1 is an alkyl having from about 3 toabout 12 carbons.
 4. Monomer of claim 1 wherein R1 is an alkyl having 3or 4 carbons.
 5. The monomer of claim 1 selected from the groupconsisting of

wherein L, contains from 1 to about 12 carbons, and R2 is hydrogen or amethyl group.
 6. Monomer of claim 5 wherein I contains from about 2 toabout 6 carbons.
 7. A monomer selected from the group consisting of:2-(4,6-dibromo-2-sec-butylphenoxy)ethyl acrylate;6-(4,6-dibromo-2-isopropylphenoxy)hexyl acrylate;2-(4,6-dibromo-2-se-butylphenoxy) 2-methyl ethyl acrylate;2-(4,6-dibromo-2-sec-butylphenoxy) 1-methyl ethyl acrylate;6-(4,6-dibromo-2-sec-butylphenoxy)hexyl acrylate;2-(4,6-dibromo-2-isopropylphenoxy)ethyl acrylate;6-(4,6-dibromo-2-dodccylphenoxy)hexyl acrylate;2-(4,6-dibromo-2-dodccylphenoxy)ethyl acrylate;2-(2,6-dibromo-4-nonylphenoxy)ethyl acrylate;2-(2,6-dibromo-4-dodccylphenoxy)ethyl acrylate;6-(4,6-dibromo-2-sec-butylphenoxy)hexyl methacrylate;6-(4,6-dibromo-2-isopropylphenoxy)hexyl methacrylate;2-(4,6-dibromo-2-sec-butylphenoxy)ethyl methacrylate;2-(4,6-dibromo-2-isopropylphenoxy)ethyl methacrylate;2-(4,6-dibromo-2-dodccylphenoxy)ethyl methacrylate;2-(2,6-dibromo-4-nonylphenoxy)ethyl methacrylate;2-(2,6-dibromo-4-dodccylphenoxy)ethyl methacrylate; and mixturesthereof.